For many years, researchers have been trying to understand what causes Alzheimer’s disease and how it develops in the brain.
A new study from Johns Hopkins Medicine, published in the Journal of Alzheimer’s Disease, suggests that serotonin, often called the “happiness” chemical, might play a bigger role in memory loss than previously thought. This discovery could change how we approach early signs of Alzheimer’s.
The study included more than 90 adults, some of whom had mild cognitive impairment (MCI) and some who did not. MCI is a condition where people start to have problems with memory and thinking that are more serious than normal aging but not as severe as Alzheimer’s disease. It’s often seen as a stepping stone between normal memory loss and full-blown Alzheimer’s.
To explore the connection, researchers used a type of brain scan called a PET scan. These scans allowed them to look closely at serotonin levels in the brain. Serotonin is a chemical that helps with mood, sleep, and memory.
What they found was quite interesting: people with MCI had lower levels of serotonin in specific areas of their brains. This is important because those same brain areas are responsible for things like thinking, memory, and emotion.
Dr. Gwenn Smith, a professor at Johns Hopkins University School of Medicine, led the research. She explained that people with MCI showed a reduction in something called the serotonin transporter. This transporter is like a recycling system for serotonin.
When it doesn’t work well, serotonin levels drop. The study found that this drop in serotonin was linked to memory problems—completely separate from other brain changes like the buildup of amyloid protein or brain shrinkage seen in Alzheimer’s.
The study is important because it shows that changes in serotonin levels might be a sign of Alzheimer’s long before people develop severe symptoms. This means doctors could start looking for these changes earlier and possibly slow down the progression of the disease with the right treatments.
To conduct the study, the team brought in 49 people with MCI and 45 healthy older adults. All participants had brain scans at Johns Hopkins between 2009 and 2022.
The researchers used PET scans to measure two things: the serotonin transporter and the buildup of amyloid-beta (Aβ) protein in the brain. Amyloid-beta is a well-known marker of Alzheimer’s disease, but this study found that low serotonin levels were also clearly linked to memory issues.
Interestingly, previous research at Johns Hopkins with mice showed that serotonin loss happened before large amounts of amyloid appeared in the brain. In those studies, the loss of serotonin was also connected to depression and anxiety. This is important because many people with Alzheimer’s also struggle with these mental health issues.
In the new study, people with MCI had up to 25% less serotonin in certain parts of their brains compared to healthy adults. These areas of the brain are responsible for memory, decision-making, and emotions. They also had more amyloid buildup, which further increases the risk of Alzheimer’s.
Dr. Smith explained that these findings could lead to new treatments. If serotonin is truly linked to memory loss and Alzheimer’s, then boosting serotonin levels might help. Some antidepressant medications already work by increasing serotonin, so they might also help with memory problems. More research is needed, but the idea is promising.
The next step for the researchers is to track people with MCI over several years to see if serotonin levels continue to drop and if that drop leads to Alzheimer’s. They also plan to look at new antidepressants that could help with both mood and memory. If these treatments work, they could slow down the disease or maybe even prevent it from getting worse.
This study is important because it opens up a new way of thinking about Alzheimer’s. For years, the main focus has been on things like amyloid plaques and tau proteins, but now serotonin is coming into the spotlight. By finding ways to protect serotonin levels in the brain, doctors might be able to slow down or even prevent memory loss.
If you or someone you know is worried about Alzheimer’s or memory problems, it may be helpful to talk to a doctor about these new findings. Understanding the role of serotonin could lead to better treatments and a brighter future for those at risk of Alzheimer’s.
If you care about Alzheimer’s, please read studies about Vitamin D deficiency linked to Alzheimer’s, vascular dementia, and Oral cannabis extract may help reduce Alzheimer’s symptoms.
For more information about brain health, please see recent studies about Vitamin B9 deficiency linked to higher dementia risk, and results showing flavonoid-rich foods could improve survival in Parkinson’s disease.
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